Blade Tip Electric Machine
An electromagnetic machine that generates electric power from an engine by having rotor poles on the tips of the fan blade airfoils and stator elements circumferentially placed around the blade airfoils. As the pole tips on the blade airfoils are excited, they rotate past the stator elements, causing a magnetic flux change in the stator. The magnetic flux change results in an electric potential that is used to provide power.
The present invention relates to electrical machines, and more particularly to electrical machines internal to gas turbine engines.
BACKGROUND OF THE INVENTIONGas turbine engines such as aero engines are required to generate electrical energy for various purposes within and external to the engine, such as to provide power for control systems or to provide electrical power to an airframe. Currently, an electrical generator that supplies electrical power required by the gas turbine engine is driven by a mechanical gearbox. The electrical generator and the mechanical gearbox are mounted within the nacelle of the engine. The size of the electrical generator is increasing to meet the increasing power demands of aircraft. For gas turbine engines that are wing- or fuselage-mounted, the increased size of the electrical generator may require enlarging the nacelle, resulting in increased aircraft drag.
One system provides an electrical machine that operates as a generator or motor, incorporated in a gas turbine engine. The compressor blades may be shrouded at the radially outer end to separate the aerodynamic part of the blades from the electrical rotor projection. Beyond the shroud, an electrical machine is provided by rotor projections attached to the compressor blade. The projections run in a channel of flux cores, resulting in an electrical machine, which is external to the combustion gas paths of the engine, for ready access, with optimized magnetic flux paths. The shroud of the blades forms a ring around the outer periphery of the gas path for containment of gases, the shroud having seals between the shroud and the walls of the channel to resist gas leakage around the shroud and into the channel.
Another system provides a mechanical link from a rotating component of the engine to a generator, in order to generate enough electrical power to meet the increased demands. Another system, in an attempt to reduce the level of mechanical complexity in the mechanical linkage system, incorporates an electrical generator within the rotating spools of the engine, preferably the high-pressure spool. However, space limitations in the region of the central axis of the engine have been found to be such that this proposal is not wholly satisfactory.
Likewise, another gas turbine engine includes an electrical generator. The generator can also be operated as a motor to provide drive, such as for starting the engine. The engine includes at least one ring of rotating blades. The motor/generator is formed from a rotating part comprising the rotating blade ring, and a fixed part comprising a plurality of coils arranged circumferentially around the blade ring. While this method reduces the complexity of the machine construction, it relies on traditional methods and system for excitation of the fan blades.
Therefore, what is needed is a method and system to utilize gas turbine fan or compressor blades as poles for an integrated electric machine for increased aircraft engine electric power generation within the existing nacelle, while providing a transverse flux electric machine suited to the structure of the fan or compressor blade tips for the excitation of the system.
SUMMARY OF THE INVENTIONThe following paragraphs summarize the embodiments of the present invention defined by the independent claims appended hereto. In one embodiment the present invention is directed to a blade tip electric machine having a transverse flux machine, a rotary blade arrangement configured with a plurality of blades and a plurality of rotor pole elements. Each rotor pole element of the plurality of rotor pole elements is disposed on a distal end of one of the plurality of blades. The blade tip electric machine also has a plurality of stator elements, where each stator element of the plurality of stator elements is circumferentially disposed and circumferentially spaced around at least a portion of the circumferential perimeter of the plurality of blades. The blade tip electric machine also has at least one coil element. The transverse flux machine provides the excitation to the rotary blade arrangement, which has a spinning motion and wherein the plurality of rotor elements pass adjacent, as opposed to through, to the plurality of stator elements thereby causing a change in magnetic flux in the at least one coil element.
Another embodiment of the present invention is directed to a gas turbine engine having a low-pressure spool turbine and a high-pressure spool turbine, a compression chamber, a booster combustion chamber, an exhaust system and a rotary blade arrangement, where the rotary blade arrangement has a plurality of blades. The blade tip electric machine also includes a plurality of rotor elements, where each rotor element of the plurality of rotor elements is disposed on a distal end of one blade of the plurality of blades. The invention also includes a plurality of stator elements, where each stator element of the plurality of stator elements is circumferentially disposed and circumferentially spaced around the circumferential perimeter of the plurality of blades. In addition, there is at least one coil element disposed on a stator element of the plurality of stator elements and the gas turbine engine has a rotary blade arrangement with a rotational motion and wherein the rotor elements pass adjacent to the plurality of stator elements thereby causing a change in magnetic flux in the stator elements in the at least one coil element.
One advantage of the present invention is an increase in aircraft engine electric power generation without further increase in nacelle size.
A further advantage of the present invention is improved blade deflection performance.
Yet another advantage of the present invention is the allowance of axial shaft movement without degradation in performance.
Still another advantage of the present invention is the incorporation of the pole with the blade's leading edge and the improved tip construction.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
DETAILED DESCRIPTION OF THE INVENTIONA high bypass aircraft gas turbine engine 10 is shown schematically in
Referring next to
As indicated in
Individual stator cores 44 are positioned to straddle a single coil 50 indicated by a broken line in
As the fan or compressor operates, each individual rotor pole 38 passes each stator core 44, and its associated stator coil 46. At the point in the rotation when the poles 38 and cores 44 are aligned, a magnetic flux path is formed. The magnetic flux path in the rotor pole 38 is indicated by arrow 54, which is generally parallel to the axis of rotation of the fan 12. The flux path in the core 44 is indicated by arrows 56, 60 and 62. The magnetic flux path then traverses the air gap 52 between the core 44 and the pole 38, flows through the core arm 44b, the core base 44 and core arm 44a, again crossing air gap 52, and back into pole 38. Because the present invention applies transverse flux in the electric machine 37, the magnetic flux does not travel radially from the fan assembly, along the entire length of the fan blades as it does in operation conventional flux machines. The shortened path of the magnetic flux makes such a machine possible, where it is used to generate electrical energy.
It can be readily understood from the above description that by the movement of the poles 38 on the blades 40 relative to the coils 46, as has been described, an electric machine 37 is capable of use either as a generator or as a motor. Thus, when the engine 10 is in operation, the coils 46 or 50 can be tapped to draw power from the engine 10 in the form of electrical power. When electric machine 37 is used as a generator, a mechanical force drives the rotor 30. In the motor capacity, the coils 46 or 50 are energized, which causes the machine to rotate, e.g., to provide a starting torque for the turbine engine.
Referring to
The novel configuration described herein allows several options previously not possible. As shown in
While the invention has been described in a fan blade configuration, the electric machine 37 may also be arranged on a compressor 16, wherein the poles 38 are attached or integrated with the blades of the compressor 16, and the remaining parts of the electric machine 37 arranged as described above. In addition, the fan blade may be arranged so that less than all of the blade tips are rotor poles. This allows for flexibility to accommodate an electrical machine design that is independent of the aerodynamic requirements, e.g., the number of fan blades required for airflow may differ from the number of magnetic poles necessary in the electrical system. Further, as the blade tips are integrated with the blade, there is little additional weight associated with the modified blade tip, so little additional centrifugal or other forces are created on the blade ring. This configuration (not shown) still provides the electric power required for the system, but does not involve each and every blade tip in the system.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements with insubstantial differences from the literal languages of the claims.
Claims
1. A blade tip electric machine comprising:
- a rotary blade arrangement, the rotary blade arrangement being configured with a plurality of blades;
- a plurality of rotor pole elements, each rotor pole element of the plurality of rotor pole elements being disposed on a distal end of one of the plurality of blades;
- a plurality of magnetically permeable stator core elements, each stator core element of the plurality of stator core elements having a slot and being circumferentially spaced around at least a portion of a circumferential perimeter of the plurality of blades;
- at least one coil element disposed within one slot of the plurality of stator core elements;
- an airgap disposed between the rotor pole elements and the plurality of magnetically permeable stator core elements; and
- wherein the rotary blade arrangement has a spinning motion and wherein the plurality of rotor elements pass adjacent to the plurality of stator elements thereby causing a change in magnetic flux and generating electric power in the at least one coil element, wherein the magnetic flux generated travels substantially radially across the airgap and substantially axially across the plurality of rotor pole elements or portions of the plurality of magnetically permeable stator core elements.
2. The machine of claim 1 wherein the at least one coil element comprises a continuous loop disposed circumferentially around the rotating blade ring.
3. The machine of claim 2 wherein each stator core element of the plurality of stator core elements are disposed to straddle the at least one coil element.
4. The machine of claim 1 wherein the at least one coil element is disposed around a center of one stator core element of the plurality of stator core elements.
5. The machine of claim 1 wherein the electric machine is configured to drive a low-pressure spool of the gas turbine engine.
6. The machine of claim 1 wherein the electric machine is configured to drive a high-pressure spool of the gas turbine engine.
7. The machine of claim 1 wherein the electric machine is configured to extract energy from the low-pressure spool of the gas turbine engine.
8. The machine of claim 1 wherein the electric machine is configured to extract energy from the high-pressure spool of the gas turbine engine.
9. The machine of claim 1 wherein the plurality of stator core elements are disposed and circumferentially spaced substantially around a circumferential perimeter of the plurality of blades.
10. The machine of claim 1 wherein the plurality of stator core elements are disposed and circumferentially spaced in an arc segment on a circumferential perimeter of the plurality of blades.
11. The machine of claim 1 wherein the rotating blade ring is selected from the group consisting of a fan blade and a compressor blade.
12. The machine of claim 1 wherein each stator core element of the plurality of stator core elements are substantially shaped in a horseshoe shape wherein the first arm segment and second arm segment are substantially parallel and the base segment is substantially perpendicular to the first and second arm segments and is dispose to connect the first and second arm segments.
13. A gas turbine engine comprising:
- at least one compressor, a combustor, a high pressure turbine and a low pressure turbines arranged in serial flow communication and disposed about a longitudinal shaft of the engine within an annular outer casing; the at least one compressor driven by the high pressure and low pressure turbines and compressor air during operation; and
- a blade tip electrical machine disposed within the annular outer casing, the blade tip electrical machine comprising: a rotary blade arrangement, the rotary blade arrangement being configured with a plurality of blades; a plurality of rotor pole elements, each rotor pole element of the plurality of rotor pole elements being disposed on a distal end of one of the plurality of blades; a plurality of magnetically permeable stator core elements, each stator core element of the plurality of stator core elements having a slot and being circumferentially spaced around at least a portion of a circumferential perimeter of the plurality of blades; at least one coil element disposed within one slot of the plurality of stator core elements; an airgap disposed between the rotor pole elements and the plurality of magnetically permeable stator core elements; and
- wherein the rotary blade arrangement has a spinning motion and wherein the plurality of rotor elements pass adjacent to the plurality of stator elements thereby causing a change in magnetic flux and generating electric power in the at least one coil element, wherein the magnetic flux generated travels substantially radially across the airgap and substantially axially across the plurality of rotor pole elements or portions of the plurality of magnetically permeable stator core elements.
14. The engine of claim 13 wherein the electric machine is configured to drive a low-pressure spool of the gas turbine engine.
15. The engine of claim 13 wherein the electric machine is configured to drive a high-pressure spool of the gas turbine engine.
16. The engine of claim 13 wherein the electric machine is configured to extract energy from the low-pressure spool of the gas turbine engine.
17. The engine of claim 13 wherein the electric machine is configured to extract energy from the high-pressure spool of the gas turbine engine.
Type: Application
Filed: Nov 29, 2006
Publication Date: May 29, 2008
Patent Grant number: 7603864
Inventors: Paul Robert Gemin (Cincinnati, OH), KiYoung Chung (West Chester, OH)
Application Number: 11/564,504
International Classification: F01D 15/10 (20060101); H02K 7/18 (20060101); F02C 6/00 (20060101); F01D 15/00 (20060101);